The present invention relates to a process for the continuous pad-dyeing or printing of continuous synthetic filament groups, for example tows and slivers of synthetic staple fibers with dyestuffs which are set under the influence of heat.
General efforts to render production processes more economical and less expensive have resulted in an increasing use of the Thermosol process for dyeing synthetic materials, for example polyester fabrics and blends of polyester fabrics. The use of the Thermosol process for polyester fabrics and its blends, especially when it is blended with cellulose fibers, often results in difficulties if a number of requirements are not exactly complied with. Particularly important is the requirement of a sustantially uniform treatment temperature during drying and dyestuff setting. Temperature variations of about 2.degree. to 3.degree. C. over the working width may lead to a varying coloration and thus render the material useless. Even the slightest of faults, such as uneven absorbency and/or bad wettability, lime precipitation, dirt and grease residues or creases become noticeable in dyeing and in most cases these faults cannot be redeemed. Thus for the Thermosol-dyeing of piece goods very exacting requirements are made regarding the pre-treatment and the conditions during the dyeing process proper. Since the Thermosol process is by far superior to the usual dyeing methods with a wet steam fixation or fixation in a liquid with respect to the economy of the process, the above-mentioned difficulties are tolerated.